SCHWARZBACH, ANDREA E.* AND ROBERT E. RICKLEFS. Department of Biology, University of Missouri, St. Louis MO 63121. - Historical biogeography of mangroves in the family Rhizophoraceae.
The ability to live exclusively in mangrove habitats evolved at least
15 times within the angiosperms. For many of those lineages it is not
clear which are their closest living relatives, when they split from
their terrestrial relatives, and how they obtained their present
distribution. We conducted a molecular phylogenetic analysis of the
family Rhizophoraceae to address these issues. Rhizophoraceae
comprises 15 genera and approximately 140 species of which four genera
and about 17 species are mangroves. In order to construct a well
supported phylogeny we used seven data sets from three sources, cpDNA
(rbcL, trnL-trnF and atpB-rbcL intergenic spacers), nuclear ribosomal
DNA (ITS1, 5.8S, ITS2) and morphology. For calibrating the molecular
data we used fossil information as well as tectonic vicariance events.
We propose the following evolutionary scenario which is concordant
with all the data available: 1. The monophyletic mangrove lineage most
likely evolved from their terrestrial sister taxon (ancestor of all
Gynotrocheae) at least 60 my ago on the shores of East Gondwana. 2.
The mangrove Rhizophoraceae moved most likely north and eastwards
through the open Tethys Sea reaching the New world at least 40 my ago.
3. All four genera (Kandelia, Bruguiera, Ceriops
and Rhizophora) underwent a severe extinction phase in the
upper Tertiary, probably after closure of the Tethys Seaway,
restricting them to the Indo-West-Pacific region. 4. The genus
Rhizophora only was re-introduced to the New World at least 11
my ago.
Key words: biogeography, extinction, mangrove, Rhizophoraceae